The oldest rock formation identified on Earth is found on the shoreline of Hudson Bay in Canada. This rock
formed 4.28 billion years ago. Which information does a scientist need to most accurately determine the age
of a rock
a) the percentage of each mineral that makes up the rock
b) the thickness of younger rock layers that cover the rock
c) the amount of each radioactive element present in the rock
d) the amount of weathering present on the surface of the rock

Subduction zones form when an oceanic plate collides with another oceanic plate or continental plate. the continental crust is lighter and less dense than oceanic crust. continental crust's density is approximately 2.7 grams per cubic centimeter. oceanic crust is thinner and the average density is about 3.3 cubic centimeters. when the two crustal plates converge the oceanic plate always bends and subducts beneath a continental plate. once the oceanic crust subjects, the rocks are subjected to changes in heat and pressure. because of this, we would expect to find rocks in the area of a subduction. a) clastic b) igneous c) metamorphic d) sedimentary